1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus that eject liquid from a nozzle orifice, and in particular to an ink jet type recording head and an ink jet type recording apparatus that eject ink as liquid.
2. Related Art
There has been know an ink jet type recording head that is an example of a liquid ejecting head equipped with, for example, an actuator unit in which piezoelectric elements and pressure generating chambers are provided, and a channel unit equipped with a nozzle plate in which nozzle orifices that are communicated with the pressure generating chambers and that eject ink is provided and reservoir forming substrate in which a reservoir that becomes a common ink chamber of the pressure generating chambers is provided (for example, see JP-A-2004-042559 (pages 6 to 8, FIGS. 1 to 2).
In such a type of ink jet type recording head, when a pressure is applied to the ink in the pressure generating chamber, a pressure wave is generated in the pressure generating chamber. The pressure wave is transmitted to the reservoir communicated with the pressure generating chamber. The pressure wave is transmitted to another pressure generating chamber via the reservoir to cause unevenness of ink ejection property such as change of liquid drop speed.
In order to solve such a problem, a compliance unit having a thin film shape having flexibility is generally provided at an opening of the reservoir unit. The compliance unit serves as a pressure change absorption function (hereinafter, referred to as compliance) to absorb energy of the pressure wave (for example, see JP-A-2007-(pages 10-12, FIG. 4)).
On the other hand, there exist a reservoir that has a portion whose width is gradually reduced at the both end in the alignment direction of the pressure generating chambers. When the both ends of the reservoir in the alignment direction of the pressure generating chambers are formed by the same width as that of the other portion of the reservoir, flow speed of the ink supplied from the center becomes slow as the ink comes close to the both ends in the alignment direction of the pressure generating chambers, and this may cause retention of bubbles at the both ends. The retention of bubbles can be prevented by forming the both ends of the reservoir in the alignment direction of the pressure generating chambers so that the widths are gradually reduced.
The energy of the pressure wave caused by pressure change in each pressure generating chamber is absorbed by the compliance unit. It is known that the absorption amount has a correlation with the length (width) of the compliance unit in the direction perpendicular to the arrangement direction of the pressure generating chambers. When the compliance unit having the same shape as the reservoir is employed to the reservoir whose width is narrow, the width of the compliance unit in the direction perpendicular to the arrangement direction of the pressure generating chambers is also narrowed. Accordingly, the energy of the pressure wave caused by pressure change in each pressure generating chamber can not fully absorbed. Accordingly, in such an ink jet type recording head, good ink ejection property can not be obtained.
Note that such a problem exists not only in the ink jet type recording head, but also in a liquid ejecting head that ejects liquid except ink in the same manner.